function y = P1998_D1(x, a, b)
% The code is based on the following paper:
%   Chen, T. Y., Lin, Y. L., and Tzeng, L. Y., forthcoming.
%   Estimating probability weighting functions through option pricing bounds. Review of Asset Pricing Studies.
%
% Copyright: Tzu-Ying Chen, Yo-Lan Lin, Larry Y. Tzeng
% Date: January 30, 2024

y = exp(- power(- b * log(x), a)) .* ...
    power(- b * log(x), a - 1) .* ...
    (a * b) ./ x;
end